I also don’t want to contribute to a feeling that masks are no longer needed because nobody is requiring them.

Maybe the best reason for vaccinated people to wear masks. Ironically, mask wearing behavior is like an epidemic - it's contagious. The more people wear masks, the more people will feel the social pressure to wear them lest they look out of step.

OTOH, I believe that the other illnesses we don't get, annoying as they are, contirbute to the health of our immune systems. In general, mask wearing may expose wearers to too few pathogens for their own good. In a time of war against a pandemic, wearing a mask is how we answer the call to duty. I'm not so sure it's a good "peacetime" strategy.